The present invention relates to a pick-up head for a component mounting machine, in particular a mounting machine for automatically mounting electronic and similar components, and it also relates to such a mounting machine and methods of mounting or placing components on substrates.
Automatic mounting machines for electronic components can be provided with a pick-up head, which fetches electronic components from different magazines and places them at accurately determined places on a circuit board. The transport from the magazine always requires some time period to be performed. Different proposals have previously been made and also been reduced to practice in existing machines in order to reduce this time period, which can be particularly embarrassing and result in that the mounting work takes a long time for the common case that many components are to be mounted on each circuit board and the pick-up head can only fetch one component in each fetching movement. In order to reduce the transport time a plurality of components can be simultaneously fetched, see the published International patent application WO 96/12394. Here a multitude of pipettes are mounted in a line configuration at a pick-up head on an X-carriage. The pipettes are movable vertically along vertical axes, which are stationary in relation to the pick-up head and to the carriage, and the pipettes can also be rotated about vertical axes to desired angular positions. However, also in this design the pick-up head must move a significant distance vertically between pick-up operations and between each delivery of a component and furthermore, also through some horizontal distance.
Picking-up pipettes or similar gripping devices in automatic component mounting machines are usually made to be capable of both a vertical movement and a rotational movement about a vertical axis which is fixed in the horizontally movable part, such as a turret or X-carriage, see e.g. the published Japanese patent applications JP 80-056095, 64-280663, 63-168096, 63-169098.
It is an object of the invention to provide a pick-up head for an automatic component mounting machine, by means of which the mounting times can be reduced and in particular the movements of the pick-up head, both vertically and horizontally, both when picking components and when delivering the components at intended places can be reduced.
Thus, a pick-up head or slide is capable of picking a plurality of components in basically one movement, i.e. substantially simultaneously, from magazines holding the components. The slide is also capable of placing the plurality of picked-up components at a circuit board in basically one movement, i.e. also substantially simultaneously. Therefor, the slide comprises a plurality of pick-up devices that are movable individually in the plane of the surface of the board at which they are to be placed. During the movements of the pick-up head from the component magazines to the board and back from the board to the component magazines, which movements are suitably made by displacing a carriage or similar device, at which the pick-up head is mounted, the relative positions of the pick-up devices are re-arranged, both by a movement in said plane and by rotating the pick-up devices if required. This relative rearrangement is necessary since the positions of the components in the magazines generally do not correspond to those positions at which the components are to be placed on the board or at which components have been placed on the board in a previous movement for placing components. The simultaneous picking and placing operations, each in basically only one movement, and the efficient use of the time period for transport between the pick-up place and the placing position result in a very fast total mounting operation and a small total mounting time.
Each pick-up device comprises advantageously a pipette, operated by a negative pressure, or a similar gripping device which has a limited movement in directions perpendicular to the surface of the board but which can be rotated about an axis perpendicular to the board and which furthermore comprises an arm. The arm is mounted in an XY-table for movements in a plane, so that the relative movements of the pipette are achieved by operating the XY-table to move the arm and thus the pipette. A plurality of such XY-tables can be mounted on top of each other on the slide.
Generally, a pick-up head or slide for an automatic mounting machine comprises as conventional at least one pick-up device, which can pick up one component in a movement in a first, usually vertical direction. Control means are associated with the pick-up device in order to displace, after picking up a component, the pick-up device in relation to the pick-up head in directions perpendicular to the first direction, typically in two horizontal directions. In particular the pick-up device can be displaced in a second direction, the second direction being substantially perpendicular to the first direction, and also in a third direction, the second direction and the third direction being substantially perpendicular to the first direction and forming a large angle to each other and preferably being perpendicular to each other. Advantageously at least two pick-up devices are provided, with each one of which an individual control means is associated for displacing a picked-up component in the perpendicular directions. The pick-up devices are mounted on a slide of the pick-up head holding the control devices, the slide performing the picking-up movement in the first direction in relation to the rest of the pick-up head. Thus all pick-up devices are given common movements in the first direction by moving the slide, both for picking components and for placing components.